<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="" method="get">
    <!--<input type="text" pattern="\d|[1-9]\d|1[0-2]\d">-->
    <input type="text" pattern="\d{3,6}">
    <input type="submit" value="提交">
</200form>
</body>
</html>